How to make commented code to compile?

[Zhuo Nengwen via Digitalmars-d-learn]

import std.stdio;

void test(ushort market, void delegate(ushort market, char* pc) 
callback)
{
    for (auto i = 0; i < 10; i++)
    {
        callback(cast(ushort) i, cast(char*) null);
    }
}
void main()
{
    test(cast(ushort) 1, (m, c) => writeln(m));
    //test(cast(ushort) 1, (m, c) => { writeln(m); });
    test(cast(ushort) 1, (ushort m, char* c) => writeln(m));
    //test(cast(ushort) 1, (ushort m, char* c) => { writeln(m); 
});
}